Which type of cancer most commonly metastasizes to the brain?

• A. Breast
• B. Lung
• C. Kidney
• D. Prostate

Answer: (B)

Brain metastases occur most often from cancers that spread through the bloodstream. Among all primary tumors, lung cancer is the leading source of brain metastases because tumor cells frequently enter the circulation and seed in the brain’s vascular-rich environment. Breast cancer also metastasizes to the brain, but not as commonly as lung cancer. Prostate cancer tends to spread to bone rather than the brain, and kidney cancer metastases to the brain are relatively uncommon. So the cancer most likely to metastasize to the brain is lung cancer.